1. Field of the Invention
The present invention relates to hand controllers and, more particularly, to hand operated controllers for operating remote systems such as the flight control systems in aircraft or spacecraft, or for control of robotics or land vehicle mechanisms.
2. Description of the Prior Art
Two and three degree of freedom hand command control systems are well known in the art. Such control systems have commonly been devised utilizing a control knob or handle, often shaped to fit the operator's hand, so that he can move it, for example in a three degree of freedom system, forwardly and backwardly to control the pitch of an aircraft, to the right and left to control the roll of the craft, and to twist it about a vertical axis to control the yaw of the aircraft. In some applications, as for example in helicopter control, a fourth command axis is needed to control the up and down motion, i.e. the collective motion of the craft. The collective control has heretofore been accomplished either by use of a separate dedicated controller or by adding a fourth axis to a three axis (roll, pitch, yaw) hand controller so that the operator lifts the control knob or handle vertically or pushes it downwardly to produce the desired collective control.
The various hand motions required have sometimes produced cross-coupling problems, i.e. where the operator in moving his wrist to produce one control accidentally also produces another control. Of all of the control motions that heretofore have existed in hand controllers, it is the fourth degree of freedom which produces the most cross-coupling difficulty for the operator. It is believed that while the operator can normally separate his operations to control roll, pitch and yaw by motions of the wrist, the adding of the fourth degree of freedom intermixes with the other motions to make it more difficult for the operator to accomplish. Furthermore, the up and down motion for the fourth degree of freedom produces muscle stress in the forearm of the operator.